Debian bug report logs - #1708
`passwd' not interruptible when invoked by `adduser'

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From olis.north.de!indrom!joey Sat Oct 21 10:36:11 1995
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From: joey@finlandia.Infodrom.North.DE (Martin Schulze)
Subject: Re: Bug#1708: `passwd' not interruptible when invoked by `adduser'
To: ian@chiark.chu.cam.ac.uk
Date: Sat, 21 Oct 1995 14:27:49 +0100 (MET)
Cc: debian-bugs@Pixar.com
In-Reply-To: <m0t65Zy-0002YGC@chiark.chu.cam.ac.uk> from "Ian Jackson" at Oct 20, 95 01:44:00 am
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Hello Ian Jackson!

}Package: adduser? miscutils?
}Version: adduser (1.94-1), miscutils (1.3-2)

No. libc.

}If I run adduser, and then decide to abort after having been presented
}with the password prompt, I can't do it with ^C.  passwd apparently
}ignores ^C, and ^D simply produces another passwd prompt.  Presumably
}I would have to type in a password twice to escape; instead, I used
}another terminal and killed the adduser process.

Because I have heavily modified the passwd program in the last days I
checked this report...

The reason is not in the adduser nor in the miscutils (or util-linux
where my passwd comes from). It's in the libc itself.

The passwd programm just makes a system call:


-- [passwd.c] --------------------------------------------------------
        pwdstr = getpass("Enter new password: ");
        if (pwdstr[0] == '\0') {
            puts("Password not changed.");
            exit(1);
        }
----------------------------------------------------------------------

Looking at the source of libc you'll find the code that is responsible
for disabling ^C:

-- [getpass.c] -------------------------------------------------------
        ttyb.c_lflag &= ~(ECHO|ISIG);
        ioctl(fileno(tty), TCSETS, &ttyb);
----------------------------------------------------------------------

The above code (from util-linux) will accept an empty password
(generated with ^D) - and won't change anything. For me this is a
correct behaviour - I can live with that.

I haven't looked at the passwd program that is used by Debian.

So far,

	Joey

-- 
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Date: Fri, 20 Oct 95 01:44 BST
From: Ian Jackson <ian@chiark.chu.cam.ac.uk>
To: Debian bugs submission address <debian-bugs@pixar.com>
Subject: `passwd' not interruptible when invoked by `adduser'

Package: adduser? miscutils?
Version: adduser (1.94-1), miscutils (1.3-2)

If I run adduser, and then decide to abort after having been presented
with the password prompt, I can't do it with ^C.  passwd apparently
ignores ^C, and ^D simply produces another passwd prompt.  Presumably
I would have to type in a password twice to escape; instead, I used
another terminal and killed the adduser process.

Ian.